MILFORD -- Nearly two years after his arrest in the 2011 death of a 4-month-old Ansonia boy, Angel Luis Santiago agreed to a plea.

The 37-year-old West Haven man accepted a plea-bargain agreement on Wednesday that could put him behind bars for 11 years when he is sentenced on March 12.

Under the terms of the deal, Santiago pleaded under the Alford doctrine -- which is not an admission of guilt, but a concession that the prosecution has enough evidence to obtain a jury conviction -- on a first-degree manslaughter charge.

Santiago was charged in the death of Kyle Robinson, whose unresponsive body was found in his mother's second-floor, Hubbell Lane, Ansonia apartment. Emergency medical personnel rushed the baby's broken body to Griffin Hospital and later transferred him to Yale-New Haven Hospital. The baby, suffering from numerous injuries to his brain, neck and spinal cord, died after lingering for nearly two days.

At the time of the incident, Santiago was dating the boy's mother, Kelly Robinson-Maresca. While the mother was at work, Santiago was watching her three children.

He has been detained in lieu of $1 million bond since surrendering to police on Dec. 19, 2011. He is in custody in Cheshire.